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The mkiv Supra Owners Club

Help identifying noise on lift-off


Mike_Mac

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Since my supra's been back on the road (stripped/cleaned/renewed both turbo and intake sides of the engine) I've started to notice a 'whooshing' sound when I lift off when #1's spooling. I've tried to get it on video here:

 

http://youtu.be/ScwKyNQfH7U

 

http://youtu.be/EENZSxCToQY

 

http://youtu.be/klabvEP3V7Y

 

To me it sounds like compressor surge at times (I think), so I'm concerned it may be the BOV and that if it is it's damaging the turbos.

 

Can anyone confirm what this could be?

Edited by Mike_Mac (see edit history)
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Not sure if that would be a good idea Chris :D.

 

Is it possible the BOV is knackered? I have just had everything off that side, replaced all the hoses and painted the metal-work. Might have given it a knock while it was off or something similar?

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If the BOV was stuck open you'd make very poor boost at lower throttle openings. If it was stuck CLOSED you may get some noise from turbo stall. I never run a BOV on any turbo engine that I build or modify, they are solely to stop noise. There's a slim chance it's not opening with vacuum applied to the small port. You'd need a vacuum pump to test it, or you could perhaps remove it, feed it a vac source from the head side of the throttle body, snap the throttle open to about 5000 RPM, then closed and see if it allows you to blow through one of the bigger ports for a second. IE, use the engine itself as a vac test source. It could also be that for some reason vacuum isn't available at the small port due to a crimped pipe or a pipe blockage.

Edited by Chris Wilson (see edit history)
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